Hyopsodontidae is an extinct

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of primitive

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s, initially assigned to the order Condylarthra, living from the

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

to the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

. Condylarthra is now thought to be a

wastebasket taxon Wastebasket taxon (also called a wastebin taxon, dustbin taxon or catch-all taxon) is a term used by some taxonomists to refer to a taxon that has the purpose of classifying organisms that do not fit anywhere else. They are typically defined by e ...

; hyopsodontids have occasionally been speculated to be related to

Afrotheria Afrotheria ( from Latin ''Afro-'' "of Africa" + ''theria'' "wild beast") is a superorder of placental mammals, the living members of which belong to groups that are either currently living in Africa or of African origin: golden moles, elephan ...

, but the most recent consensus is that they are related to

Perissodactyla Perissodactyla (, ), or odd-toed ungulates, is an order of ungulates. The order includes about 17 living species divided into three families: Equidae (horses, asses, and zebras), Rhinocerotidae (rhinoceroses), and Tapiridae (tapirs). They t ...

. Analysis of the inner ear shows shared characteristics with the Equoidea (horses and paleotheres); they may be a basal

ungulate Ungulates ( ) are members of the diverse clade Euungulata ("true ungulates"), which primarily consists of large mammals with Hoof, hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined ...

group near to perissodactyls. They were generally small

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

s, like many early mammals. The most common genus is '' Hyopsodus''. Members of the family were small by modern standards, ranging in size from a small rat to a raccoon. The hyopsodontids had many primitive mammal characteristics, including five-toed feet with claws and a complete dentition: a full set of incisors, canines, premolars, and molars. During the Paleocene in Europe, they reached a high diversity level, starting with '' Louisina'' and '' Monshyus'' in Hainin, Belgium, and following in the Cernaysian beds with '' Tricuspiodon'', '' Paratricuspiodon'', and '' Paschatherium''. High levels of diversity are also seen in Western North America in the Eocene within the genus '' Hyopsodus'', with up to 18 named species, some of which are specific to particular locations over short spans of geologic time. This pattern suggests that at least some hyosodontids became quite specialized for specific ways of life. The group was not especially long-lived, but highly successful for its time, with fossil material in some areas suggesting large numbers of individuals.

List of genera

* '' Aletodon'' * '' Dorraletes'' * '' Haplaletes'' * '' Haplomylus'' * '' Hyopsodus'' * '' Litomylus'' * '' Paratricuspiodon'' * '' Paschatherium'' * '' Phenacodaptes'' * '' Tricuspiodon''

References

{{Taxonbar, from=Q2638459 Prehistoric mammal families Paleocene mammals Danian first appearances Eocene extinctions Condylarths Taxa named by Édouard Louis Trouessart Ungulates